A fuel cell includes an electrode that provokes an electrochemical reaction between a fuel and an oxidizing agent, a polymer electrolyte membrane that transfers protons generated by the reaction, and a separator that supports the electrode and the polymer electrolyte membrane.
In general, a polymer electrolyte fuel cell is used as the fuel cell for a vehicle since it has high efficiency, high current and output densities, and a short starting time. Further, the polymer electrolyte fuel cell does not corrode, and does not need to regulate an electrolyte because it uses a polymer electrolyte, compared to other types of fuel cells.
In addition, since the polymer electrolyte fuel cell is an environmentally friendly power source that produces no exhaust emission except pure water, research has been extensively conducted in this field.
Such an electrolyte fuel cell may generate electrical energy while generating water and heat through an electrochemical reaction between a fuel including hydrogen and an oxidizing agent such as air.
In other words, in the electrolyte fuel cell, the fuel is divided into hydrogen ions and electrons in a catalyst of the anode electrode, and the hydrogen ions cross over to a cathode through a polymer electrolyte membrane such that electrical energy is generated and water is produced from the combination of the oxidizing agent and the electrons injected from external wires.
In a fuel cell used for a vehicle, individual unit cells are stacked to obtain a required potential, and the stacked structure of unit cells is referred to as a stack.
The electrode of the fuel cell is formed by mixing a hydrogen ion carrier and a catalyst, and the activity of the electrochemical reaction may decrease in an initial operation after the fuel cell is manufactured because a transfer port is blocked and the carrier may not reach the catalyst. Further, the carrier of hydrogen ions forming a triple phase interface is not easily hydrolyzed in the initial operation, and continuous mobility of the hydrogen ions and the electrons is difficult to secure.
Accordingly, activation and performance evaluation of the fuel cell stack are performed to secure the performance of the fuel cell after assembling a membrane-electrode assembly including the electrode, the polymer electrolyte membrane, and the stack which is an assembly of fuel cells for generating electricity including separators.
The activation and performance evaluation remove remaining impurities that flow in a process of manufacturing the membrane-electrode assembly and the stack, activate sites that do not participate in the reaction, secure a passage in which reactants move to the catalyst, and secure a hydrogen ion passage by sufficiently hydrolyzing an electrolyte included in the polymer electrolyte membrane and the electrode.
The above described activation of the fuel cell stack has been applied in various methods of the related art. The main method of activation is to detect a voltage of the fuel cell while operating the stack for a substantial period of time under a predetermined voltage.
Accordingly, a system for activating the fuel cell stack according to the related art may perform the activation of the fuel cell stack and evaluation by supplying the fuel and the oxidizing agent into the fuel cells after manufacturing the stack in which a plurality fuel cells are layered, and by monitoring the voltage of the fuel cells while applying the electrical energy generated by the fuel cells to an electric load apparatus.
In activating the fuel cell stack and evaluating the performance, connectors of a voltage measuring system are connected to a terminal that protrudes from each fuel cell. An output cable connected to the electric load apparatus is connected to output terminals at both sides of the stack, and a fluid supply pipe for supplying fluids (e.g., hydrogen, air, and coolant) is connected to a manifold of the stack.
In the process of connecting the connectors of the voltage measurement system to the terminals that protrude from each fuel cell of the stack, the connectors and the terminals of each fuel cell are manually connected. Accordingly, in the related art, the connectors of the voltage measuring system are manually connected to the terminals of the stack, thus deteriorating workability. Further, a long period of time is required for the overall process for connecting the connectors and the terminals, and stack damage may occur when connecting the terminals.
In addition, in the process of connecting the output cables connected to the electric load apparatus to the output terminals at both sides of the stack, a worker clamps a bus bar connected to the electric load apparatus and the output cable to the output terminal of both sides of the stack with a bolt. Accordingly, in the related art, when manually connecting and detaching the output cable to/from the output terminal on both sides of the stack, he worker may be exposed to a danger of electric shock. In other words, since a current may be generated due to the electro-chemical reaction between remaining hydrogen and air even when supply of the hydrogen and air to the stack discontinues, an accidental electric shock of a worker may be induced when detaching the output cable from the terminal.
Further, in the process of connecting the fluid supply pipe for supplying fluids to the fuel cells of the stack to the manifold of the stack, the stack is connected to the fluid supply pipe of an activating device by manually pushing the stack. Accordingly, in the related art, workability may be deteriorated, and air-tightness may not be secured when connecting the fluid supply pipe to the stack manifold since the stack weighting dozens of kilograms is connected to the fluid supply pipe of the activating device by manually pushing.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention, and therefore, it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.